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The interaction potentials between O(lD) and methane and the potential surface for the reaction have been calculated by the ab initio MRDCI method. The minimum energy path of the reaction is an almost collinear approach of O(lD) to one of the hydrogen atoms of methane up to the position of rOH = 1.66 A. A very low potential barrier (2.1 kcal mol-') exists along the path, and then the oxygen atom migrates off-axis. The surface correlates to the stable methanol structure. The product channel to yield CH3 + O H and also the one to yield CH3O + H are both directly derived from the potential minimum corresponding to the stable methanol structure without any exit potential barriers. Possible reaction dynamics on the surface are discussed.

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Endosymbiotic bacterium Wolbachia interacts with host in either a mutualistic or parasitic manner. Wolbachia is frequently identified in various arthropod species, and to date, Wolbachia infections have been detected in different insects. Here, we found a triple Wolbachia infection in Homona magnanima, a serious tea pest, and investigated the effects of three infecting Wolbachia strains (wHm-a, -b, and -c) on the host. Starting with the triple-infected host line (W), which was collected in western Tokyo in 1999 and maintained in laboratory, we established an uninfected line (W) and three singly infected lines (W, W, and W) using antibiotics. Mating experiments with the host lines revealed that only wHm-b induced cytoplasmic incompatibility (CI) in H. magnanima, with the intensities of CI different between the W and W lines. Regarding mutualistic effects, wHm-c shortened larval development time and increased pupal weight in both the W and W lines to the same extent, whereas no distinct phenotype was observed in lines singly infected with wHm-a. Based on quantitative PCR analysis, Wolbachia density in the W line was higher than in the other host lines (p < 0.01, n = 10). Wolbachia density in the W line was also higher than in the W and W lines, while no difference was observed between the W and W lines. These results indicate that the difference in the CI intensity between a single or multiple infection may be attributed to the difference in wHm-b density. However, no correlation was observed between mutualistic effects and Wolbachia density.

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Although it is known that osteoclasts are multinucleated cells that are responsible for bone resorption, the mechanism by which their size is regulated is unclear. We previously reported that an actin-rich superstructure, termed the zipper-like structure, specifically appears during the fusion of large osteoclast-like cells (OCLs). Actin cytoskeleton reorganization in osteoclasts is regulated by a signaling network that includes the macrophage colony-stimulating factor (M-CSF) receptor, a proto-oncogene, Src, and small GTPases. Here, we examined the role of actin reorganization in the multinucleation of OCLs differentiated from RAW 264.7 cells using various pharmacological agents. Jasplakinolide, which stabilizes actin stress fibers, induced the development of small OCLs, and the Src inhibitor SU6656 and the dynamin inhibitor dynasore impaired the maintenance of the podosome belt and the zipper-like structure. These inhibitors decreased the formation of large OCLs but increased the number of small OCLs. M-CSF is known to stimulate osteoclast fusion. M-CSF signaling via Src up-regulated Rac1 activity but down-regulated Rho activity. Rac1 and Rho localized to the center of the zipper-like structure. Rho activator II promoted the formation of small OCLs, whereas the Rho inhibitor Y27632 promoted the generation of large OCLs. These results suggest that the status of the actin cytoskeleton signaling network determines the size of OCLs during cell fusion.